LAUSR

Severe, ‘treatment-resistant’ depressions may respond to treatment with a classic monoamine oxidase inhibitor (MAOI) even when myriad trials with other antidepressant classes have failed (Bodkin & Dunlop, 2021). These drugs have a unique pharmacological profile as irreversible inhibitors of both MAO-isoforms A and B, resulting in increased levels of the three major monoamine neurotransmitters serotonin, norepinephrine, and dopamine—which may explain their superior antidepressant (AD) effect. The classic MAOIs are phenelzine, tranylcypromine, and isocarboxazid. The recent publication of the first ever expert-consensus guideline—The Prescriber’s Guide to Classic MAO-Inhibitors (Van den Eynde et al., 2022a)—will increase the usage of these essential drugs. Thus, it is important that psychiatric nurses update their knowledge on caring for MAOI patients. There are three topics of particular note: (A) the dietary precautions, (B) the drug-drug interactions, and (C) the management of orthostatic hypotension and its treatment implications. A. Treatment with a classic MAOI results in the reduced breakdown rate of tyramine, a vasoactive monoamine that is found in some foods and drinks. While certain dietary precautions are required to prevent hypertensive reactions, the MAOI diet is neither difficult nor overly restrictive. Modern food hygiene and production standards have resulted in significantly lowered tyramine levels in most all foods and drinks. It is important and sufficient that healthy dietary patterns are maintained, and that some attention is given to portion control and the avoidance of a select few items—e.g., certain aged cheeses, fermented meat products, and spontaneously fermented beers. The Prescriber’s Guide to the MAOI Diet (Van den Eynde et al., 2022b) can be consulted for detailed information. B. The drug-drug interactions are comprehensively described in the Prescriber’s Guide (Van den Eynde et al., 2022a). Comedication with serotonergic drugs must be avoided; these are drugs with significant action as a serotonin reuptake inhibitor (e.g., SSRIs, SNRIs, certain opioid analgesics) or serotonin-releaser (e.g., amphetamines at medium/ high doses). The combination may precipitate serotonin toxicity (or ‘serotonin syndrome’)—this is a dose-related reaction which can be severe. Early recognition is key; the main symptoms are tremor, hyperreflexia, and clonus (Gillman, 2006). C. MAOIs have a dose-related blood pressure (BP) lowering effect that manifests as orthostatic hypotension, which attenuates over time. Typically, this BP-effect coincides with the onset of the MAOI’s therapeutic effect (although additional dose increases may be indicated), and is maximal after ∼14 days on a particular MAOI dose. A gradual reduction in the degree of orthostatic hypotension is expected to occur in the subsequent days/weeks if the same MAOI dose is maintained. There are several options to alleviate the burden of this side-effect; they include spreading and/or temporarily reducing the daily MAOI dose, and implementing various measures to achieve orthostatic normotension such as increasing fluid and salt intake (Figueroa et al., 2010), and maintaining or establishing a good baseline activity level (whilst monitoring the risks of low BPinduced dizziness and fainting). Thus, maintaining a BP log book in the early phase of MAOI treatment is a worthwhile endeavour from which valuable clinical information can be derived (Figure 1). Above all, the take-home message is that MAOIs remain an invaluable—and safe—tool in the treatment kit for difficult-to-treat depressions.